Building off this post: http://tech.yipit.com/2012/09/05/deploying-from-github-the-right-way/ We need a way to add deploy keys with Che...

Our solution is to use a new deploy key for every run and then clean them
up later with a batch job. However, this doesn’t really solve the problem,
just makes it so that now the valuable thing is your Github API key. Unsure
if there is a good way to use a the hosts ssh-agent from Vagrant, though
you may be able to hack something together with a Vagrant plugin.

I haven’t tried this, but you can specify JSON data in your Vagrantfile.

If your deploy process gets your deploy key from an attribute, you can
override that in the Vagrantfile. And, since a Vagrantfile is just ruby,
you could get that key from just reading in a user’s SSH public key file.